InterviewSolution
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InterviewSolution
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Interpration of the rate law: For a hydrothertical reaction `X+Y+Zrazrr` products the rate law is determined to be `"Rate" =k[X][Y]^(2)` What happens to the reaction rate when we make each of the following concentration changes ? (a) We dobule the concentration of X without changing the concentration of Y or Z. (b) We double the concentration of Y without changing the concentration of X or Z. (c ) We double the concentrations of Z without changing the concentration of X or Y. (d) We double all three concentrations simultaneously. Strategy: Interpret the law to predict the changes in reaction rate. Remember that changing concentrations does not change the value of k. |
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Answer» (a) According to the rate law expression, reaction is directly proportional to the first power of [X]. If we do not change [Y] or [Z], then doubling [X] (i.e., increasing [X] by a factor of 2) cause the reaction rate to increase by a factor of `2^(1)=2`, so the reaction rate doubles. (b) Rate is directly proportional to the second power of [Y]. If we do not change [X] or [Z], then doubling [Y] (i.e., increasing [Y] by a factor of 2) cause the reaction rate to increase by a factor of `2^(2)=4`, so the reaction rate quadruples. (c ) The reaction rate is indepent of [Z] so changing [Z] causes no change in reaction rate. (d) Doubling all concentrations would cause the changes decscribed in (a), (b), and (c ) simultaneouly. The rate would incerase by a factor of 2 due to the change in [X], by a factor of 4 due to the change in [Y], and be unaffected by the change in [Z]. The result is that the reaction rate increases by a factor of `2^(1)xx2^(2)=8`. |
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